In a noteworthy accomplishment, the Indian Space Research Organisation (ISRO) has achieved the successful Halo-Orbit Insertion (HOI) for the Aditya-L1 solar observatory spacecraft on January 6, 2024, at around 16:00 Hrs (IST).
Aditya-L1 now follows a periodic Halo orbit positioned approximately 1.5 million km from Earth along the Sun-Earth line, boasting an orbital period of around 177.86 earth days. This carefully chosen orbit, offering several advantages, ensures a mission lifespan of 5 years, minimizes the need for station-keeping maneuvers, reduces fuel consumption, and guarantees a continuous, unobstructed view of the Sun.
The primary objective of the Aditya-L1 mission is to observe and comprehend the chromospheric and coronal dynamics of the Sun from the Lagrangian point L1. Opting for a Halo orbit around L1 over a Low Earth Orbit (LEO) presents specific benefits:
Consistent Sun-Spacecraft Velocity Change: The Halo orbit provides a consistent Sun-spacecraft velocity change, making it ideal for helioseismology.
Beyond Earth’s Magnetosphere: Positioned outside Earth’s magnetosphere, Aditya-L1 is apt for “in situ” sampling of the solar wind and particles.
Uninterrupted Sun Observation: The Halo orbit allows continuous Sun observation and an unobstructed view of Earth, facilitating seamless communication with ground stations.
Halo Orbit Insertion Process:
The insertion process initiated as the spacecraft crossed the XZ plane in the Sun-Earth-L1 rotating system. This maneuver involved nullifying the X and Z velocity components and achieving the required Y-velocity for the Halo orbit. The specific Halo orbit parameters for Aditya-L1 are Ax: 209200 km, Ay: 663200 km, and Az: 120000 km.
This successful insertion marks a critical phase demanding precise navigation, continuous monitoring, and adjustments of the spacecraft’s speed and position using onboard thrusters. ISRO’s success not only underscores its prowess in intricate orbital maneuvers but also instills confidence for future interplanetary missions.
Designed at UR Rao Satellite Centre (URSC), Aditya-L1 features payloads developed by Indian scientific laboratories, including IIA, IUCAA, and ISRO. Launched on September 2, 2023, aboard PSLV-C57, Aditya-L1 embarked on a progressive journey towards the Sun-Earth-L1 Lagrange point, increasing its orbital size with five liquid engine burns during the Earth orbit phase. Two trajectory correction maneuvers (TCM-1 and TCM-2) were executed to ensure compliance with Halo orbit insertion conditions.
As Aditya-L1 enters this new phase, all payloads have been rigorously tested and confirmed to perform satisfactorily. The successful Halo-Orbit Insertion not only advances solar observations but also positions India as a significant player in the realm of space exploration. The graphic below visually captures the accomplishment of the HOI condition on January 6, 2024, symbolized by the red dot, signifying minimum fuel consumption. The final firing aligned the spacecraft with the Halo Orbit, a pivotal maneuver ensuring optimal mission conditions. Without the HOI, the spacecraft would have followed a different trajectory, as illustrated in the graphic.
